PIK3CA and neoplasm: KDR/VEGFR2 gene (4q12) encodes KDR/VEGFR2–Kinase insert domain receptor/Vascular endothelial growth factor receptor 2 protein (1356 amino acids; 151,527 Da), which functions as a surface receptor for VEGFC, VEGFD, and especially VEGFA proteins, sustaining angiogenic (endothelial proliferation, survival, migration, tubular morphogenesis, and blood vessel sprouting) and tumor (tumor growth, invasion, and therapeutic resistance) processes via HIF-1–VEGF–TGFB, PLCγ–PKC–MEK–MAPK, and PI3K/AKT signaling pathways [124,125].